Imaging lens, and electronic apparatus including the same

ABSTRACT

An imaging lens includes first to sixth lens elements arranged from an object side to an image side in the given order. Through designs of surfaces of the lens elements and relevant optical parameters, a short system length of the imaging lens may be achieved while maintaining good optical performance.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Chinese Application No.201310385034.2, filed on Aug. 29, 2013.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an imaging lens and an electronicapparatus including the same.

2. Description of the Related Art

In recent years, as use of portable electronic devices (e.g., mobilephones and digital cameras) becomes ubiquitous, much effort has been putinto reducing dimensions of portable electronic devices. Moreover, asdimensions of charged coupled device (CCD) and complementary metal-oxidesemiconductor (CMOS) based optical sensors are reduced, dimensions ofimaging lenses for use with the optical sensors must be correspondinglyreduced without significantly compromising optical performance.

U.S. Pat. No. 8,355,215 discloses an imaging lens with six lenselements, which has a system length of 2 cm. Although the imaging lenshas acceptable image quality, its large size is not suitable forelectronic devices that tend to have a small thickness, which may rangefrom 1 cm to 2 cm.

U.S. Pat. No. 8,432,619 discloses an imaging lens with six lenselements, which has a system length of 0.5 cm, satisfying requirementsof reduced thickness. However, it has image distortion of 25%. Such poorimage quality cannot fulfill specification requirements of consumerelectronic products.

Reducing the system length of the imaging lens while maintainingsatisfactory optical performance is always a goal in the industry.

SUMMARY OF THE INVENTION

Therefore, an object of the present invention is to provide an imaginglens that has a shorter overall length while maintaining good opticalperformance.

According to one aspect of the present invention, an imaging lenscomprises a first lens element, a second lens element, a third lenselement, a fourth lens element, a fifth lens element and a sixth lenselement arranged in order from an object side to an image side along anoptical axis of the imaging lens. Each of the first lens element, thesecond lens element, the third lens element, the fourth lens element,the fifth lens element and the sixth lens element has a refractivepower, and has an object-side surface facing toward the object side andan image-side surface facing toward the image side.

The refractive power of the first lens element is positive.

The object-side surface of the second lens element has a concave portionin a vicinity of the optical axis.

The refractive power of the third lens element is negative, and theimage-side surface of the third lens element has a concave portion in avicinity of the optical axis.

The object-side surface of the fourth lens element has a concave portionin a vicinity of the optical axis, and the image-side surface of thefourth lens element has a convex portion in a vicinity of the opticalaxis.

The image-side surface of the sixth lens element has a concave portionin a vicinity of the optical axis, and a convex portion in a vicinity ofa periphery of the sixth lens element.

The imaging lens does not include any lens element with refractive powerother than the first lens element, the second lens element, the thirdlens element, the fourth lens element, the fifth lens element and thesixth lens element.

Another object of the present invention is to provide an electronicapparatus having an imaging lens with six lens elements.

According to another aspect of the present invention, an electronicapparatus includes a housing and an imaging module. The imaging moduleis disposed in the housing, and includes the imaging lens of the presentinvention, a barrel on which the imaging lens is disposed, a holder uniton which the barrel is disposed, and an image sensor disposed at theimage side of the imaging lens.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the present invention will becomeapparent in the following detailed description of the preferredembodiments with reference to the accompanying drawings, of which:

FIG. 1 is a schematic diagram to illustrate the structure of a lenselement;

FIG. 2 is a schematic diagram that illustrates the first preferredembodiment of an imaging lens according to the present invention;

FIG. 3 shows values of some optical parameters corresponding to theimaging lens of the first preferred embodiment;

FIG. 4 shows values of some parameters of an optical relationshipcorresponding to the imaging lens of the first preferred embodiment;

FIGS. 5(a) to 5(d) show different optical characteristics of the imaginglens of the first preferred embodiment;

FIG. 6 is a schematic diagram that illustrates the second preferredembodiment of an imaging lens according to the present invention;

FIG. 7 shows values of some optical parameters corresponding to theimaging lens of the second preferred embodiment;

FIG. 8 shows values of some parameters of an optical relationshipcorresponding to the imaging lens of the second preferred embodiment;

FIGS. 9(a) to 9(d) show different optical characteristics of the imaginglens of the second preferred embodiment;

FIG. 10 is a schematic diagram that illustrates the third preferredembodiment of an imaging lens according to the present invention;

FIG. 11 shows values of some optical parameters corresponding to theimaging lens of the third preferred embodiment;

FIG. 12 shows values of some parameters of an optical relationshipcorresponding to the imaging lens of the third preferred embodiment;

FIGS. 13(a) to 13(d) show different optical characteristics of theimaging lens of the third preferred embodiment;

FIG. 14 is a schematic diagram that illustrates the fourth preferredembodiment of an imaging lens according to the present invention;

FIG. 15 shows values of some optical parameters corresponding to theimaging lens of the fourth preferred embodiment;

FIG. 16 shows values of some parameters of an optical relationshipcorresponding to the imaging lens of the fourth preferred embodiment;

FIGS. 17(a) to 17(d) show different optical characteristics of theimaging lens of the fourth preferred embodiment;

FIG. 18 is a schematic diagram that illustrates the fifth preferredembodiment of an imaging lens according to the present invention;

FIG. 19 shows values of some optical parameters corresponding to theimaging lens of the fifth preferred embodiment;

FIG. 20 shows values of some parameters of an optical relationshipcorresponding to the imaging lens of the fifth preferred embodiment;

FIGS. 21(a) to 21(d) show different optical characteristics of theimaging lens of the fifth preferred embodiment;

FIG. 22 is a schematic diagram that illustrates the sixth preferredembodiment of an imaging lens according to the present invention;

FIG. 23 shows values of some optical parameters corresponding to theimaging lens of the sixth preferred embodiment;

FIG. 24 shows values of some parameters of an optical relationshipcorresponding to the imaging lens of the sixth preferred embodiment;

FIGS. 25(a) to 25(d) show different optical characteristics of theimaging lens of the sixth preferred embodiment;

FIG. 26 is a schematic diagram that illustrates the seventh preferredembodiment of an imaging lens according to the present invention;

FIG. 27 shows values of some optical parameters corresponding to theimaging lens of the seventh preferred embodiment;

FIG. 28 shows values of some parameters of an optical relationshipcorresponding to the imaging lens of the seventh preferred embodiment;

FIGS. 29(a) to 29(d), show different optical characteristics of theimaging lens of the seventh preferred embodiment;

FIG. 30 is a schematic diagram that illustrates the eighth preferredembodiment of an imaging lens according to the present invention;

FIG. 31 shows values of some optical parameters corresponding to theimaging lens of the eighth preferred embodiment;

FIG. 32 shows values of some parameters of an optical relationshipcorresponding to the imaging lens of the eighth preferred embodiment;

FIGS. 33(a) to 33(d) show different optical characteristics of theimaging lens of the eighth preferred embodiment;

FIG. 34 is a table that lists values of parameters of other opticalrelationships corresponding to the imaging lenses of the first to eighthpreferred embodiments;

FIG. 35 is a schematic partly sectional view to illustrate a firstexemplary application of the imaging lens of the present invention; and

FIG. 36 is a schematic partly sectional view to illustrate a secondexemplary application of the imaging lens of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Before the present invention is described in greater detail, it shouldbe noted that like elements are denoted by the same reference numeralsthroughout the disclosure.

In the following description, “a lens element has a positive (ornegative) refractive power” means the lens element has a positive (ornegative) refractive power in a vicinity of an optical axis thereof. “Anobject-side surface (or image-side surface) has a convex (or concave)portion at a certain area” means that, compared to a radially exteriorarea adjacent to said certain area, said certain area is more convex (orconcave) in a direction parallel to the optical axis. Referring to FIG.1 as an example, the lens element is radially symmetrical with respectto an optical axis (I) thereof. The object-side surface of the lenselement has a convex portion at an area A, a concave portion at an areaB, and a convex portion at an area C. This is because the area A is moreconvex in a direction parallel to the optical axis (I) in comparisonwith a radially exterior area thereof (i.e., area B), the area B is moreconcave in comparison with the area C, and the area C is more convex incomparison with an area E. “In a vicinity of a periphery” refers to anarea around a periphery of a curved surface of the lens element forpassage of imaging light only, which is the area C in FIG. 1. Theimaging light includes a chief ray Lc and a marginal ray Lm. “In avicinity of the optical axis” refers to an area around the optical axisof the curved surface for passage of the imaging light only, which isthe area A in FIG. 1. In addition, the lens element further includes anextending portion E for installation into an optical imaging lensdevice. Ideally, the imaging light does not pass through the extendingportion E. The structure and shape of the extending portion E are notlimited herein. In the following embodiments, the extending portion E isnot depicted in the drawings for the sake of clarity.

Referring to FIG. 2, the first preferred embodiment of an imaging lens10 according to the present invention includes an aperture stop 2,first, second, third, fourth, fifth and sixth lens elements 3-8, and anoptical filter 9 arranged in the given order along an optical axis (I)from an object side to an image side. The optical filter 9 is aninfrared cut filter for selectively absorbing infrared light to therebyreduce imperfection of images formed at an image plane 100. It should benoted that the present invention uses an image sensor (not shown)packaged using COB (chip on board) techniques. Compared to theconventional CSP (chip scale package), a cover glass is not required forthe COB technique. Hence, the imaging lens of the present invention doesnot include the cover glass.

Each of the first, second, third, fourth, fifth and sixth lens elements3-8 and the optical filter 9 has an object-side surface 31, 41, 51, 61,71, 81, 91 facing toward the object side, and an image-side surface 32,42, 52, 62, 72, 82, 92 facing toward the image side. Light entering theimaging lens 10 travels through the aperture stop 2, the object-side andimage-side surfaces 31, 32 of the first lens element 3, the object-sideand image-side surfaces 41, 42 of the second lens element 4, theobject-side and image-side surfaces 51, 52 of the third lens element 5,the object-side and image-side surfaces 61, 62 of the fourth lenselement 6, the object-side and image-side surfaces 71, 72 of the fifthlens element 7, the object-side and image-side surfaces 81, 82 of thesixth lens element 8, and the object-side and image-side surfaces 91, 92of the optical filter 9, in the given order, to form an image on theimage plane 100. Each of the object-side surfaces 31, 41, 51, 61, 71, 81and the image-side surfaces 32, 42, 52, 62, 72, 82 is aspherical and hasa center point coinciding with the optical axis (I).

The lens elements 3-8 are made of a plastic material in this embodiment,and at least one of the lens elements 3-8 may be made of other materialsin other embodiments.

In the first preferred embodiment, which is depicted in FIG. 2, thefirst lens element 3 has a positive refractive power. The object-sidesurface 31 of the first lens element 3 has a convex portion 311 in avicinity of the optical axis (I), and a convex portion 312 in a vicinityof a periphery of the first lens element 3. The image-side surface 32 ofthe first lens element 3 has a convex portion 321 in a vicinity of theoptical axis (I), and a convex portion 322 in a vicinity of a peripheryof the first lens element 3.

The second lens element 4 has a positive refractive power. Theobject-side surface 41 of the second lens element 4 has a concaveportion 411 in a vicinity of the optical axis (I), and a convex portion412 in a vicinity of a periphery of the second lens element 4. Theimage-side surface 42 of the second lens element 4 is a convex surfacethat has a convex portion 421 in a vicinity of the optical axis (I), anda convex portion 422 in a vicinity of a periphery of the second lenselement 4.

The third lens element 5 has a negative refractive power. Theobject-side surface 51 of the third lens element 5 has a concave portion511 in a vicinity of the optical axis (I), and a convex portion 512 in avicinity of a periphery of the third lens element 5. The image-sidesurface 52 of the third lens element 5 is a concave surface that has aconcave portion 521 in a vicinity of the optical axis (I), and a concaveportion 522 in a vicinity of the periphery of the third lens element 5.

The fourth lens element 6 has a positive refractive power. Theobject-side surface 61 of the fourth lens element 6 is a concave surfacethat has a concave portion 611 in a vicinity of the optical axis (I),and a concave portion 612 in a vicinity of a periphery of the fourthlens element 6. The image-side surface 62 of the fourth lens element 6is a convex surface that has a convex portion 621 in a vicinity of theoptical axis (I), and a convex portion 622 in a vicinity of theperiphery of the fourth lens element 6.

The fifth lens element 7 has a positive refractive power. Theobject-side surface 71 of the fifth lens element 7 is a concave surfacethat has a concave portion 711 in a vicinity of the optical axis (I),and a concave portion 712 in a vicinity of a periphery of the fifth lenselement 7. The image-side surface 72 of the fifth lens element 7 is aconvex surface that has a convex portion 721 in a vicinity of theoptical axis (I), and a convex portion 722 in a vicinity of theperiphery of the fifth lens element 7.

The sixth lens element 8 has a negative refractive power. Theobject-side surface 81 of the sixth lens element 8 has a concave portion811 in a vicinity of the optical axis (I), and a convex portion 812 in avicinity of a periphery of the sixth lens element 8. The image-sidesurface 82 of the sixth lens element 8 has a concave portion 821 in avicinity of the optical axis (I), and a convex portion 822 in a vicinityof the periphery of the sixth lens element 8.

In the first preferred embodiment, the imaging lens 10 does not includeany lens element with refractive power other than the abovementionedfirst to sixth lens elements 3-8.

Shown in FIG. 3 is a table that lists values of some optical parameterscorresponding to the surfaces 31-91, 32-92 of the first preferredembodiment. The imaging lens 10 has an overall system effective focallength (EFL) of 3.977 mm, a half field-of-view (HFOV) of 37.807°, anF-number of 2.022, and a system length of 5.502 mm. The system lengthrefers to a distance between the object-side surface 31 of the firstlens element 3 and the image plane 100.

In this embodiment, each of the object-side surfaces 31-81 and theimage-side surfaces 32-82 is aspherical, and satisfies the opticalrelationship of

$\begin{matrix}{{Z(Y)} = {{\frac{Y^{2}}{R}/\left( {1 + \sqrt{1 - {\left( {1 + K} \right)\frac{Y^{2}}{R^{2}}}}} \right)} + {\sum\limits_{i = 1}^{n}\;{a_{i} \times Y^{i}}}}} & (1)\end{matrix}$

where:

R represents a radius of curvature of the aspherical surface;

Z represents a depth of an aspherical surface, which is defined as aperpendicular distance between an arbitrary point on the asphericalsurface that is spaced apart from the optical axis (I) by a distance Y,and a tangent plane at a vertex of the aspherical surface at the opticalaxis (I);

Y represents a perpendicular distance between the arbitrary point on theaspherical surface and the optical axis (I);

K represents a conic constant; and

a_(i) represents a i^(th) aspherical coefficient.

Shown in FIG. 4 is a table that lists values of some optical parametersof the aforementioned optical relationship (1) corresponding to thefirst preferred embodiment.

Relationships among some of the aforementioned optical parameterscorresponding to the first preferred embodiment are as follows:TTL=5.504ALT=3.521(T1+T3+T4+T5+T6)/T2=9.258(T1+T2+T3+T4+T6)/T5=4.368(G12+G23+G45+G56)/T2=0.806ALT/T5=5.868TTL/T5=9.173ALT/G34=5.088TTL/T4=6.348

where:

TTL represents a distance between the object-side surface 31 of thefirst lens element 3 and the image plane 100 at the optical axis (I);

ALT represents a sum of a distance between the object-side surface 31and the image-side surface 32 of the first lens element 3 at the opticalaxis (I), a distance between the object-side surface 41 and theimage-side surface 42 of the second lens element 4 at the optical axis(I), a distance between the object-side surface 51 and the image-sidesurface 52 of the third lens element 5 at the optical axis (I), adistance between the object-side surface 61 and the image-side surface62 of the fourth lens element 6 at the optical axis (I), a distancebetween the object-side surface 71 and the image-side surface 72 of thefifth lens element 7 at the optical axis (I), and a distance between theobject-side surface 81 and the image-side surface 82 of the sixth lenselement 8 at the optical axis (I);

T1 represents the distance between the object-side surface 31 and theimage-side surface 32 of the first lens element 3 at the optical axis(I);

T2 represents the distance between the object-side surface 41 and theimage-side surface 42 of the second lens element 4 at the optical axis(I);

T3 represents the distance between the object-side surface 51 and theimage-side surface 52 of the third lens element 5 at the optical axis(I);

T4 represents the distance between the object-side surface 61 and theimage-side surface 62 of the fourth lens element 6 at the optical axis(I);

T5 represents the distance between the object-side surface 71 and theimage-side surface 72 of the fifth lens element 7 at the optical axis(I);

T6 represents the distance between the object-side surface 81 and theimage-side surface 82 of the sixth lens element 8 at the optical axis(I);

G12 represents a distance between the image-side surface 32 of the firstlens element 3 and the object-side surface 41 of the second lens element4 at the optical axis (I);

G23 represents a distance between the image-side surface 42 of thesecond lens element 4 and the object-side surface 51 of the third lenselement 5 at the optical axis (I);

G34 represents a distance between the image-side surface 52 of the thirdlens element 5 and the object-side surface 61 of the fourth lens element6 at the optical axis (I);

G45 represents a distance between the image-side surface 62 of thefourth lens element 6 and the object-side surface 71 of the fifth lenselement 7 at the optical axis (I); and

G56 represents a distance between the image-side surface 72 of the fifthlens element 7 and the object-side surface 81 of the sixth lens element8 at the optical axis (I).

FIG. 5(a) shows simulation results corresponding to longitudinalspherical aberration of the first preferred embodiment. FIGS. 5(b) to5(d) respectively show simulation results corresponding to sagittalastigmatism aberration, tangential astigmatism aberration, anddistortion aberration of the first preferred embodiment at the imageplane 100. In each of the simulation results, curves correspondingrespectively to wavelengths of 470 nm, 588 nm, and 650 nm are shown.

It can be understood from FIG. 5(a) that, since each of the curvescorresponding to longitudinal spherical aberration has a focal length ateach field of view (indicated by the vertical axis) that falls withinthe range of ±0.05 mm, the first preferred embodiment is able to achievea relatively low spherical aberration at each of the wavelengths.Furthermore, since the curves corresponding to longitudinal sphericalaberration are close to each other, the first preferred embodiment has arelatively low chromatic aberration.

It can be understood from FIGS. 5(b) and 5(c) that, since each of thecurves falls within the range of ±0.2 mm of focal length, the firstpreferred embodiment has a relatively low optical aberration.

Moreover, as shown in FIG. 5(d), since each of the curves correspondingto distortion aberration falls within the range of ±1%, the firstpreferred embodiment is able to meet requirements in imaging quality ofmost optical systems.

In view of the above, even with the system length reduced down to 5.502mm, the imaging lens 10 of the first preferred embodiment is still ableto achieve a relatively good optical performance.

Referring to FIG. 6, the differences between the first and secondpreferred embodiments of the imaging lens 10 of this invention reside inthat: the object-side surface 31 of the first lens element 3 has aconcave portion 311 in a vicinity of a periphery of the first lenselement 3; the object-side surface 41 of the second lens element 4 has aconcave portion 413 in a vicinity of a periphery of the second lenselement 4, and a convex portion 414 between a concave optical axisportion thereof and the concave portion 413; the image-side surface 62of the fourth lens element 6 has a concave portion 623 in a vicinity ofa periphery of the fourth lens element 6; the object-side surface 71 ofthe fifth lens element 7 has a convex portion 711 between an opticalaxis portion thereof and a periphery portion thereof; and theobject-side surface 81 of the sixth lens element 8 has a concave portion813 in a vicinity of a periphery of the sixth lens element 8, and theimage-side surface 82 of the sixth lens element 8 has a convex portion823 and a concave portion 824 between the concave portion 821 and theconvex portion 822.

Shown in FIG. 7 is a table that lists values of some optical parameterscorresponding to the surfaces 31-91, 32-92 of the second preferredembodiment. The imaging lens 10 has an overall system focal length of4.173 mm, an HFOV of 36.616°, an F-number of 2.044, and a system lengthof 5.531 mm.

Shown in FIG. 8 is a table that lists values of some optical parametersof the aforementioned optical relationship (1) corresponding to thesecond preferred embodiment.

Relationships among some of the aforementioned optical parameterscorresponding to the second preferred embodiment are as follows:TTL=5.531ALT=3.323(T1+T3+T4+T5+T6)/T2=6.130(T1+T2+T3+T4+T6)/T5=2.817(G12+G23+G45+G56)/T2=0.533ALT/T5=4.196TTL/T5=6.984ALT/G34=3.640TTL/T4=19.407

FIGS. 9(a) to 9(d) respectively show simulation results corresponding tolongitudinal spherical aberration, sagittal astigmatism aberration,tangential astigmatism aberration, and distortion aberration of thesecond preferred embodiment. It can be understood from FIGS. 9(a), 9(b),9(c) and 9(d) that the second preferred embodiment is able to achieve arelatively good optical performance.

Referring to FIG. 10, the differences between the first and thirdpreferred embodiments of the imaging lens 10 of this invention reside inthat: the object-side surface 31 of the first lens element 3 has aconcave portion 311 in a vicinity of a periphery of the first lenselement 3; the object-side surface 51 of the third lens element 5 has aconcave portion 513 in a vicinity of a periphery of the third lenselement 5; and the object-side surface 81 of the sixth lens element 8has a concave portion 813 in a vicinity of a periphery of the sixth lenselement 6, and the image-side surface 82 of the sixth lens element 8 hasa convex portion 823 and a concave portion 824 between the concaveportion 821 and the convex portion 822.

Shown in FIG. 11 is a table that lists values of some optical parameterscorresponding to the surfaces 31-91, 32-92 of the third preferredembodiment. The imaging lens 10 has an overall system focal length of4.0248 mm, an HFOV of 37.533°, an F-number of 2.02, and a system lengthof 5.420 mm.

Shown in FIG. 12 is a table that lists values of some optical parametersof the aforementioned optical relationship (1) corresponding to thethird preferred embodiment.

Relationships among some of the aforementioned optical parameterscorresponding to the third preferred embodiment are as follows:TTL=5.419ALT=3.007(T1+T3+T4+T5+T6)/T2=7.253(T1+T2+T3+T4+T6)/T5=9.026(G12+G23+G45+G56)/T2=2.936ALT/T5=11.137TTL/T5=20.070ALT/G34=5.294TTL/T4=5.479

FIGS. 13(a) to 13(d) respectively show simulation results correspondingto longitudinal spherical aberration, sagittal astigmatism aberration,tangential astigmatism aberration, and distortion aberration of thethird preferred embodiment. It can be understood from FIGS. 13(a),13(b), 13(c) and 13(d) that the third preferred embodiment is able toachieve a relatively good optical performance.

Referring to FIG. 14, the differences between the first and fourthpreferred embodiments of the imaging lens 10 of this invention reside inthat: the object-side surface 31 of the first lens element 3 has aconcave portion 311 in a vicinity of a periphery of the first lenselement 3; the object-side surface 41 of the second lens element 4 has aconcave portion 413 in a vicinity of a periphery of the second lenselement 4, and a convex portion 415 between a concave optical axisportion thereof and the convex portion 413; and the object-side surface51 of the third lens element 5 has a convex portion 514 in a vicinity ofthe optical axis (I), and a concave portion 513 in a vicinity of aperiphery of the third lens element 5.

Shown in FIG. 15 is a table that lists values of some optical parameterscorresponding to the surfaces 31-91, 32-92 of the fourth preferredembodiment. The imaging lens 10 has an overall system focal length of3.931 mm, an HFOV of 38.127°, an F-number of 2.004, and a system lengthof 5.309 mm.

Shown in FIG. 16 is a table that lists values of some optical parametersof the aforementioned optical relationship (1) corresponding to thefourth preferred embodiment.

Relationships among some of the aforementioned optical parameterscorresponding to the fourth preferred embodiment are as follows:TTL=5.310ALT=3.298(T1+T3+T4+T5+T6)/T2=6.590(T1+T2+T3+T4+T6)/T5=4.099(G12+G23+G45+G56)/T2=0.643ALT/T5=5.609TTL/T5=9.031ALT/G34=4.457TTL/T4=7.618

FIGS. 17(a) to 17(d) respectively show simulation results correspondingto longitudinal spherical aberration, sagittal astigmatism aberration,tangential astigmatism aberration, and distortion aberration of thefourth preferred embodiment. It can be understood from FIGS. 17(a),17(b), 17(c) and 17(d) that the fourth preferred embodiment is able toachieve a relatively good optical performance.

Referring to FIG. 18, the differences between the first and fifthpreferred embodiments of the imaging lens 10 of this invention reside inthat: the object-side surface 51 of the third lens element 5 has aconcave portion 513 in a vicinity of a periphery of the third lenselement 5; and the object-side surface 71 of the fifth lens element 7has a convex portion 712 in a vicinity of a periphery of the fifth lenselement 7, and the image-side surface 72 of the fifth lens element 7 hasa concave portion 722 in a vicinity of a periphery of the fifth lenselement 7.

Shown in FIG. 19 is a table that lists values of some optical parameterscorresponding to the surfaces 31-91, 32-92 of the fifth preferredembodiment. The imaging lens 10 has an overall system focal length of3.851 mm, an HFOV of 38.705°, an F-number of 2.054, and a system lengthof 5.312 mm.

Shown in FIG. 20 is a table that lists values of some optical parametersof the aforementioned optical relationship (1) corresponding to thefifth preferred embodiment.

Relationships among some of the aforementioned optical parameterscorresponding to the fifth preferred embodiment are as follows:TTL=5.313ALT=3.227(T1+T3+T4+T5+T6)/T2=6.975(T1+T2+T3+T4+T6)/T5=9.058(G12+G23+G45+G56)/T2=0.627ALT/T5=11.089TTL/T5=18.258ALT/G34=4.355TTL/T4=7.790

FIGS. 21(a) to 21(d) respectively show simulation results correspondingto longitudinal spherical aberration, sagittal astigmatism aberration,tangential astigmatism aberration, and distortion aberration of thefifth preferred embodiment. It can be understood from FIGS. 21(a),21(b), 21(c) and 21(d) that the fifth preferred embodiment is able toachieve a relatively good optical performance.

Referring to FIG. 22, the differences between the first and sixthpreferred embodiments of the imaging lens 10 of this invention reside inthat: the object-side surface 31 of the first lens element 3 has aconcave portion 311 in a vicinity of a periphery of the first lenselement 3; the object-side surface 41 of the second lens element 4 has aconcave portion 413 in a vicinity of a periphery of the second lenselement 4, and a convex portion 415 between a concave optical axisportion thereof and the concave portion 413; the object-side surface 51of the third lens element 5 has a concave portion 513 in a vicinity of aperiphery of the third lens element 5; and the object-side surface 71 ofthe fifth lens element 7 has a convex portion 713 in a vicinity of theoptical axis (I).

Shown in FIG. 23 is a table that lists values of some optical parameterscorresponding to the surfaces 31-91, 32-92 of the sixth preferredembodiment. The imaging lens 10 has an overall system focal length of3.911 mm, an HFOV of 38.320°, an F-number of 2.008, and a system lengthof 5.353 mm.

Shown in FIG. 24 is a table that lists values of some optical parametersof the aforementioned optical relationship (1) corresponding to thesixth preferred embodiment.

Relationships among some of the aforementioned optical parameterscorresponding to the sixth preferred embodiment are as follows:TTL=5.352ALT=3.117(T1+T3+T4+T5+T6)/T2=6.317(T1+T2+T3+T4+T6)/T5=3.711(G12+G23+G45+G56)/T2=0.694ALT/T5=5.212TTL/T5=8.950ALT/G34=4.075TTL/T4=7.668

FIGS. 25(a) to 25(d) respectively show simulation results correspondingto longitudinal spherical aberration, sagittal astigmatism aberration,tangential astigmatism aberration, and distortion aberration of thesixth preferred embodiment. It can be understood from FIGS. 25(a),25(b), 25(c) and 25(d) that the sixth preferred embodiment is able toachieve a relatively good optical performance.

Referring to FIG. 26, the differences between the first and seventhpreferred embodiments of the imaging lens 10 of this invention reside inthat: the image-side surface 32 of the first lens element 3 has aconcave portion 321 in a vicinity of the optical axis (I), and a convexportion 322 in a vicinity of a periphery of the first lens element 3;the object-side surface 51 of the third lens element 5 has a convexportion 514 in a vicinity of the optical axis (I), and a concave portion513 in a vicinity of a periphery of the third lens element 5; and theobject-side surface 81 of the sixth lens element 8 is a concave surfacethat has a concave portion 813 in a vicinity of a periphery of the sixthlens element 8.

Shown in FIG. 27 is a table that lists values of some optical parameterscorresponding to the surfaces 31-91, 32-92 of the seventh preferredembodiment. The imaging lens 10 has an overall system focal length of3.889 mm, an HFOV of 36.710°, an F-number of 2.211, and a system lengthof 5.301 mm.

Shown in FIG. 28 is a table that lists values of some optical parametersof the aforementioned optical relationship (1) corresponding to theseventh preferred embodiment.

Relationships among some of the aforementioned optical parameterscorresponding to the seventh preferred embodiment are as follows:TTL=5.302ALT=3.242(T1+T3+T4+T5+T6)/T2=7.653(T1+T2+T3+T4+T6)/T5=3.928(G12+G23+G45+G56)/T2=1.194ALT/T5=5.430TTL/T5=8.881ALT/G34=3.555TTL/T4=8.552

FIGS. 29(a) to 29(d) respectively show simulation results correspondingto longitudinal spherical aberration, sagittal astigmatism aberration,tangential astigmatism aberration, and distortion aberration of theseventh preferred embodiment. It can be understood from FIGS. 29(a),29(b), 29(c) and 29(d) that the seventh preferred embodiment is able toachieve a relatively good optical performance.

Referring to FIG. 30, the differences between the first and eighthpreferred embodiments of the imaging lens 10 of this invention reside inthat: the object-side surface 51 of the third lens element 5 has aconcave portion 513 in a vicinity of a periphery of the third lenselement 5; the object-side surface 71 of the fifth lens element 7 has aconvex portion 713 in a vicinity of the optical axis (I), and theimage-side surface 72 of the fifth lens element 7 has a concave portion723 between an convex optical axis portion 721 thereof and a convexperiphery portion 722 thereof; and the object-side surface 81 of thesixth lens element 8 is a concave surface that has a concave portion 813in a vicinity of a periphery of the sixth lens element 8.

Shown in FIG. 31 is a table that lists values of some optical parameterscorresponding to the surfaces 31-91, 32-92 of the eighth preferredembodiment. The imaging lens 10 has an overall system focal length of4.405 mm, an HFOV of 35.699°, an F-number of 2.007, and a system lengthof 5.904 mm.

Shown in FIG. 32 is a table that lists values of some optical parametersof the aforementioned optical relationship (1) corresponding to theeighth preferred embodiment.

Relationships among some of the aforementioned optical parameterscorresponding to the eighth preferred embodiment are as follows:TTL=5.940ALT=3.414(T1+T3+T4+T5+T6)/T2=5.889(T1+T2+T3+T4+T6)/T5=5.611(G12+G23+G45+G56)/T2=2.936ALT/T5=7.248TTL/T5=12.611ALT/G34=6.253TTL/T4=5.017

FIGS. 33(a) to 33(d) respectively show simulation results correspondingto longitudinal spherical aberration, sagittal astigmatism aberration,tangential astigmatism aberration, and distortion aberration of theeighth preferred embodiment. It can be understood from FIGS. 33(a),33(b), 33(c) and 33(d) that the eighth preferred embodiment is able toachieve a relatively good optical performance.

Shown in FIG. 34 is a table that lists the aforesaid relationships amongsome of the aforementioned optical parameters corresponding to the eightpreferred embodiments for comparison. When each of the opticalparameters of the imaging lens 10 according to this invention satisfiesthe following optical relationships, the optical performance is stillrelatively good even with the reduced system length, so that applicationof the present invention to portable electronic devices may contributeto thickness reduction of the devices.

(1) When (G12+G23+G45+G56)/T2≦3.0, a sum of G12, G23, G45 and G56 has arelatively large reducible ratio compared to T2, which may effectivelycontribute to reduction of the overall dimension of the imaging lens 10,thereby favoring miniaturization. Preferably,0.5≦(G12+G23+G45+G56)/T2≦3.0.

(2) When ALT/T5 is greater than 4.0, T5 has a relatively large reducibleratio compared to ALT, which may effectively contribute to reduction ofthe overall system length of the imaging lens 10, thereby favoringminiaturization. Preferably, 4.0≦ALT/T5≦12.0.

(3) TTL/T5≧6.8: Since the fifth lens element 7 usually has a relativelylarge effective optical radius, T5 may be made thicker. Reduction of T5favors reducing system length of the imaging lens 10. When thisrelationship is satisfied, T5 has a relatively large reducible ratiocompared to TTL, which may effectively contribute to reduction of theoverall system length of the imaging lens 10, thereby favoringminiaturization. Preferably, 6.8≦TTL/T5≦21.0.

(4) When (T1+T2+T3+T4+T6)/T5≧2.8, T5 has a relatively large reducibleratio compared to T1, T2, T3, T4 and T6, which may contribute toreduction of the system length while maintaining image quality.Preferably, 2.8≦(T1+T2+T3+T4+T6)/T5≦10.0.

(5) When (T1+T3+T4+T5+T6)/T2≦9.3, a sum of T1, T3, T4, T5 and T6 has arelatively large reducible ratio compared to T2, which may effectivelycontribute to reduction of the overall system length of the imaging lens10, thereby favoring miniaturization. Preferably,5.0≦(T1+T3+T4+T5+T6)/T2≦9.3.

(6) When TTL/T4≦20.0, T4 has a relatively small reducible ratio comparedto TTL. Considering optical properties and manufacturing ability, betterarrangement may be achieved when this relationship is satisfied.Preferably, 5.0≦TTL/T4≦20.0.

(7) When ALT/G34≦5.3, G34 has a relatively small reducible ratiocompared to ALT, so as to maintain a better distance between the thirdlens element 5 and the fourth lens element 6, thereby achieving goodimage quality. Preferably, 3.5≦ALT/G34≦5.3.

To sum up, effects and advantages of the imaging lens 10 according tothe present invention are described hereinafter.

1. By virtue of the convex portions 421, the convex portion 721, or theconcave portion 811, optical aberration of images may be corrected.Since the lens elements 3-8 are made of a plastic material, weight andcost of the imaging lens 10 may be reduced.

2. Through design of the relevant optical parameters, such as(T1+T3+T4+T5+T6)/T2, (T1+T2+T3+T4+T6)/T5, (G12+G23+G45+G56)/T2, ALT/T5,TTL/T5, ALT/G34, and TTL/T4, optical aberrations, such as sphericalaberration, may be reduced or even eliminated. Further, through surfacedesign and arrangement of the lens elements 3-8, even with the systemlength reduced, optical aberrations may still be reduced or eveneliminated, resulting in relatively good optical performance.

3. Through the aforesaid eight preferred embodiments, it is known thatthe system length of this invention may be reduced down to below 6 mm,so as to facilitate developing thinner relevant products with economicbenefits.

Shown in FIG. 35 is a first exemplary application of the imaging lens10, in which the imaging lens 10 is disposed in a housing 11 of anelectronic apparatus 1 (such as a mobile phone, but not limitedthereto), and forms a part of an imaging module 12 of the electronicapparatus 1. The imaging module 12 includes a barrel 21 on which theimaging lens 10 is disposed, a holder unit 120 on which the barrel 21 isdisposed, and an image sensor 130 disposed at the image plane 100 (seeFIG. 2).

The holder unit 120 includes a first holder portion 121 in which thebarrel 21 is disposed, and a second holder portion 122 having a portioninterposed between the first holder portion 121 and the image sensor130. The barrel 21 and the first holder portion 121 of the holder unit120 extend along an axis (II), which coincides with the optical axis (I)of the imaging lens 10.

Shown in FIG. 36 is a second exemplary application of the imaging lens10. The differences between the first and second exemplary applicationsreside in that, in the second exemplary application, the holder unit 120is configured as a voice-coil motor (VCM), and the first holder portion121 includes an inner section 123 in which the barrel 21 is disposed, anouter section 124 that surrounds the inner section 123, a coil 125 thatis interposed between the inner and outer sections 123, 124, and amagnetic component 126 that is disposed between an outer side of thecoil 125 and an inner side of the outer section 124.

The inner section 123 and the barrel 21, together with the imaging lens10 therein, are movable with respect to the image sensor 130 along anaxis (III), which coincides with the optical axis (I) of the imaginglens 10. The optical filter 9 of the imaging lens 10 is disposed at thesecond holder portion 122, which is disposed to abut against the outersection 124. Configuration and arrangement of other components of theelectronic apparatus 1 in the second exemplary application are identicalto those in the first exemplary application, and hence will not bedescribed hereinafter for the sake of brevity.

By virtue of the imaging lens 10 of the present invention, theelectronic apparatus 1 in each of the exemplary applications may beconfigured to have a relatively reduced overall thickness with goodoptical and imaging performance, so as to reduce cost of materials, andsatisfy requirements of product miniaturization.

While the present invention has been described in connection with whatare considered the most practical and preferred embodiments, it isunderstood that this invention is not limited to the disclosedembodiments but is intended to cover various arrangements includedwithin the spirit and scope of the broadest interpretation so as toencompass all such modifications and equivalent arrangements.

What is claimed is:
 1. An imaging lens comprising a first lens element,a second lens element, a third lens element, a fourth lens element, afifth lens element and a sixth lens element arranged in order from anobject side to an image side along an optical axis of said imaging lens,each of said first lens element, said second lens element, said thirdlens element, said fourth lens element, said fifth lens element and saidsixth lens element having a refractive power, and having an object-sidesurface facing toward the object side and an image-side surface facingtoward the image side, wherein: the refractive power of said first lenselement is positive; said object-side surface of said second lenselement has a concave portion in a vicinity of the optical axis, andsaid image-side surface of said second lens element has a convex portionin a vicinity of the optical axis; the refractive power of said thirdlens element is negative, and said image-side surface of said third lenselement has a concave portion in a vicinity of the optical axis; therefractive power of said fourth lens element is positive, saidobject-side surface of said fourth lens element has a concave portion ina vicinity of the optical axis, said image-side surface of said fourthlens element having a convex portion in a vicinity of the optical axis;and said image-side surface of said sixth lens element has a concaveportion in a vicinity of the optical axis, and a convex portion in avicinity of a periphery of said sixth lens element, wherein saidobject-side surface of said sixth lens element has a concave portion ina vicinity of the optical axis; wherein said imaging lens does notinclude any lens element with refractive power other than said firstlens element, said second lens element, said third lens element, saidfourth lens element, said fifth lens element and said sixth lenselement.
 2. The imaging lens as claimed in claim 1, satisfying (G12 +G23+G45 +G56 )/T2≦3.0, where G12 represents a distance between saidimage-side surface of said first lens element and said object-sidesurface of said second lens element at the optical axis; G23 representsa distance between said image-side surface of said second lens elementand said object-side surface of said third lens element at the opticalaxis; G45 represents a distance between said image-side surface of saidfourth lens element and said object-side surface of said fifth lenselement at the optical axis; G56 represents a distance between saidimage-side surface of said fifth lens element and said object-sidesurface of said sixth lens element at the optical axis; and T2represents a distance between said object-side surface and saidimage-side surface of said second lens element at the optical axis. 3.The imaging lens as claimed in claim 2, further satisfying ALT/T5≧4.0,where ALT represents a sum of a distance between said object-sidesurface and said image-side surface of said first lens element at theoptical axis, the distance between said object-side surface and saidimage-side surface of said second lens element at the optical axis, adistance between said object-side surface and said image-side surface ofsaid third lens element at the optical axis, a distance between saidobject-side surface and said image-side surface of said fourth lenselement at the optical axis, a distance between said object-side surfaceand said image-side surface of said fifth lens element at the opticalaxis, and a distance between said object-side surface and saidimage-side surface of said sixth lens element at the optical axis; andT5 represents the distance between said object-side surface and saidimage-side surface of said fifth lens element at the optical axis. 4.The imaging lens as claimed in claim 1, satisfying TTL/T5≧6.8, where TTLrepresents a distance between said object-side surface of said firstlens element and an image plane at the image side of said imaging lensat the optical axis; and T5 represents a distance between saidobject-side surface and said image-side surface of said fifth lenselement at the optical axis.
 5. The imaging lens as claimed in claim 4,further satisfying (G12+G23+G45+G56)/T2≦3.0,where G12 represents adistance between said image-side surface of said first lens element andsaid object-side surface of said second lens element at the opticalaxis; G23 represents a distance between said image-side surface of saidsecond lens element and said object-side surface of said third lenselement at the optical axis; G45 represents a distance between saidimage-side surface of said fourth lens element and said object-sidesurface of said fifth lens element at the optical axis; G56 represents adistance between said image-side surface of said fifth lens element andsaid object-side surface of said sixth lens element at the optical axis;and T2 represents a distance between said object-side surface and saidimage-side surface of said second lens element at the optical axis. 6.The imaging lens as claimed in claim 1, satisfying(T1+T2+T3+T4+T6)/T5≧2.8, where T1 represents a distance between saidobject-side surface and said image-side surface of said first lenselement at the optical axis; T2 represents a distance between saidobject-side surface and said image-side surface of said second lenselement at the optical axis; T3 represents a distance between saidobject-side surface and said image-side surface of said third lenselement at the optical axis; T4 represents a distance between saidobject-side surface and said image-side surface of said fourth lenselement at the optical axis; T5 represents a distance between saidobject-side surface and said image-side surface of said fifth lenselement at the optical axis; and T6 represents a distance between saidobject-side surface and said image-side surface of said sixth lenselement at the optical axis.
 7. The imaging lens as claimed in claim 6,further satisfying (G12+G23+G45+Gp6)/T2≦3.0, where G12 represents adistance between said image-side surface of said first lens element andsaid object-side surface of said second lens element at the opticalaxis; G23 represents a distance between said image-side surface of saidsecond lens element and said object-side surface of said third lenselement at the optical axis; G45 represents a distance between saidimage-side surface of said fourth lens element and said object-sidesurface of said fifth lens element at the optical axis; and G56represents a distance between said image-side surface of said fifth lenselement and said object-side surface of said sixth lens element at theoptical axis.
 8. The imaging lens as claimed in claim 7, wherein saidimage-side surface of said fifth lens element has a convex portion in avicinity of the optical axis.
 9. The imaging lens as claimed in claim 1,satisfying (T1+T3+T4+T5+T6)/T2≦9.3, where T1 represents a distancebetween said object-side surface and said image-side surface of saidfirst lens element at the optical axis; T2 represents a distance betweensaid object-side surface and said image-side surface of said second lenselement at the optical axis; T3 represents a distance between saidobject-side surface and said image-side surface of said third lenselement at the optical axis; T4 represents a distance between saidobject-side surface and said image-side surface of said fourth lenselement at the optical axis; T5 represents a distance between saidobject-side surface and said image-side surface of said fifth lenselement at the optical axis; and T6 represents a distance between saidobject-side surface and said image-side surface of said sixth lenselement at the optical axis.
 10. The imaging lens as claimed in claim 1,satisfying TTL/T4≧20.0, where TTL represents a distance between saidobject-side surface of said first lens element and an image plane at theimage side of said imaging lens at the optical axis; and T4 represents adistance between said object-side surface and said image-side surface ofsaid fourth lens element at the optical axis, and the refractive powerof said second lens element is positive.
 11. The imaging lens as claimedin claim 10, further satisfying (T1+T2+T3+T4+T6)/T5≧2.8, where T1represents a distance between said object-side surface and saidimage-side surface of said first lens element at the optical axis; T2represents a distance between said object-side surface and saidimage-side surface of said second lens element at the optical axis; T3represents a distance between said object-side surface and saidimage-side surface of said third lens element at the optical axis; T5represents a distance between said object-side surface and saidimage-side surface of said fifth lens element at the optical axis; andT6 represents a distance between said object-side surface and saidimage-side surface of said sixth lens element at the optical axis. 12.The imaging lens as claimed in claim 11, further satisfying(G12+G23+G45+G56)/T2≦3.0, where G12 represents a distance between saidimage-side surface of said first lens element and said object-sidesurface of said second lens element at the optical axis; G23 representsa distance between said image-side surface of said second lens elementand said object-side surface of said third lens element at the opticalaxis; G45 represents a distance between said image-side surface of saidfourth lens element and said object-side surface of said fifth lenselement at the optical axis; and G56 represents a distance between saidimage-side surface of said fifth lens element and said object-sidesurface of said sixth lens element at the optical axis.
 13. The imaginglens as claimed in claim 1, wherein said image-side surface of saidfifth lens element has a convex portion in a vicinity of the opticalaxis.
 14. The imaging lens as claimed in claim 13, satisfying:ALT/G34≧5.3, where ALT represents a sum of a distance between saidobject-side surface and said image-side surface of said first lenselement at the optical axis, a distance between said object-side surfaceand said image-side surface of said second lens element at the opticalaxis, a distance between said object-side surface and said image-sidesurface of said third lens element at the optical axis, a distancebetween said object-side surface and said image-side surface of saidfourth lens element at the optical axis, a distance between saidobject-side surface and said image-side surface of said fifth lenselement at the optical axis, and a distance between said object-sidesurface and said image-side surface of said sixth lens element at theoptical axis; and G34 represents a distance between said image-sidesurface of said third lens element and said object-side surface of saidfourth lens element at the optical axis.
 15. An electronic apparatuscomprising: a housing; and an imaging module disposed in said housing,and including an imaging lens as claimed in claim 1, a barrel on whichsaid imaging lens is disposed, a holder unit on which said barrel isdisposed, and an image sensor disposed at the image side of said imaginglens.